The book is set in a world of roughly the same technological level as the Napoleonic Wars. The protagonist is Emily Marshwic, the middle sister of a family of proud lineage but lately diminished wealth. Emily's country, the kingdom of Lascanne, is engaged in a war with neighbouring Denland, which was an ally until a revolution in Denland overthrew its monarchy. To stop the ravaging hordes of bloodthirsty revolutionaries from plunging Lascanne into the same chaos, the good and noble king of Lascanne leads his people in a heroic defence of their beloved country or that's how most people in Lascanne see it, anyway. The only person who'll present things to Emily in a different light is Mr. Northway, an old enemy of her family and everyone knows how corrupt and cynical he is, so she's not about to believe him.
The authorities perpetually claim the war is "almost won", and yet, the army always seems to need more and more people conscripted into it. Emily's family does its bit first her brother-in-law goes to war, then her brother. But when the word eventually comes that one woman from every household will be conscripted too, Emily herself marches off. The battlefield is a hellish swamp, the military leadership doesn't inspire much confidence, and the Denlanders aren't the ill-disciplined rabble people say and on top of it all, the authorities may have been dishonest about more than just the progress of the war.
The book contains examples of:
- 0% Approval Rating: Mr. Northway, Mayor-Governor of Chalcaster, is widely unpopular everyone knows him to be corrupt, and the aristocrats who are just as bad nevertheless view him as a shabby commoner who they'd rather not have at parties. Emily and her family have particular reason to dislike him, but she finds that he's used to being disliked and doesn't take it amiss and is even relatively kind to her. Their relationship develops over the course of the war, but his approval rating with the rest of the town remains low, and once he starts working for the victorious foreign occupiers he becomes somehow even less popular, despite his efforts to mitigate their rule and keeping some level of consistency in the town.
- The Alcoholic: Father Burnloft, the priest attached to the army in which Emily is sent to serve, is habitually drunk. It may simply be a consequence of all the death he's seen, but soldiers who've seen just as much and now have to listen to him stagger through the funeral service for their dead comrades don't necessarily have much sympathy.
- An Arm and a Leg: Emily's brother-in-law, Tubal, finishes the war minus a leg. All told he's not too bitter about it, considering he made it home at the very least.
- Bittersweet Ending: Emily survives, and at least some of the people she cares about survive too (including the one she had developed feelings for). As a bonus, the person responsible for the war is dead. However, this occurs against the backdrop of her country having lost the war, and now being under foreign occupation. This is less of a downer then might have been assumed at the start of the book, though, since the foreigners weren't the ones who started it and aren't the crazy anarchists they were portrayed as. Of course all this is in addition to the fact that both countries have been devastated by the war and are looking at difficult times ahead.
- Conscription: How both armies are filling their ranks. Emily's brother-in-law, her brother and then she herself are drafted. Most of the soldiers Emily meets had entirely mundane jobs before the war and he Denland army isn't much different, with even the leader of the Denland army in Levant apparently being a former Doctor. The repeated conscription is also an early sign that the war isn't going as well as the official news says it is. Drafting all men from 15 to 50 and the decision for an otherwise very patriarchal society to draft women into the army show the desperate state the Lascanne army is actually in.
- Courier: Penny Belchere is an official military courier for the kingdom of Lascanne, and is the first woman most of the characters have seen in army uniform. It's an early sign that Lascanne is running out of male conscripts and is thinking about how women can be put in military roles, which presages Emily's own conscription. (Penny Belchere herself shows up again a number of times, including once when her supposedly non-front-line role doesn't stop her getting captured.)
- Dangerous Deserter: With most able-bodied men away fighting in the war, a gang of men who theoretically should be fighting in the war see an opportunity to prey on undefended lands well behind the front lines. Wealthier households such as Emily's are prime targets, especially when they contain Emily's sister Alice, who's unwise enough to be lured a supposed romantic rendezvous by a hostage-seeking bandit.
- Deconstruction: The novel deconstructs Politically Correct History and does a realistic take on the concept of female soldiers fighting alongside men in a historical period where this wouldn't have been the case. Lascanne is depicted as a very patriarchal nation with Stay in the Kitchen attitudes being the norm. Guns of the Dawn explores the question of what would drive a sexist country like Lascanne into conscripting women for their army. The answer? Total desperation. Despite constant reports of imminent victory, their Technologically Advanced Foe is winning. The military is facing a severe Mook Depletion as a result of an outdated army fighting against unknown, more advanced weapons and tactics. With all of Lascanne's able-bodied men dead, wounded or already enlisted, the kingdom's only option for continuing the war is to enlist women, many of whom are unprepared for war and only given minimal training.
- De-Power: Warlocks get their powers from their king, so when Denland's monarchy fell, it was left without warlocks to bolster its army in the war against Lascanne. This also comes up at end of the book, when the fact that Lascanne's King is still alive after their surrender means all his remaining warlocks are still active. Due to the near impossibility of imprisoning them, Denland intends to execute them all, including Emily's romantic interest Giles Scavian. Emily killing her own country's king also depowers the remaining warlocks, meaning there is no need to execute him.
- Fantasy Gun Control: Averted. Despite the existence of Kings who can create fire-throwing warlocks, the setting not only features muskets, trains, and other similar technology but Denland's "secret weapon" in the war isn't Applied Phlebotinum or Magitek muskets, but simply a new invention Dr. Lam refers to as "the rifle", as well as more advanced artillery. It turns out that a firearm with more accuracy and range than your enemies can be just as deadly as any Military Mage. Moreso, since, unlike Lascanne's warlocks, rifles can be mass-produced.
- Foolish Sibling, Responsible Sibling: The Marshwic family has Mary and Emily, who tend towards the serious, and Alice, who is interested in balls and dresses despite the family not really having the money to support that kind of lifestyle any more, and of course an ongoing war. It's played with a bit, though, in that Alice's determination to lead a properly aristocratic social life is revealed to be partly motivated by her belief that a good marriage is the only way to alleviate the financial troubles that keep the others so glum. On the other hand, her good motivations don't make her any smarter, as proven when she runs away to meet someone who turns out to be a ransom-seeking outlaw.
- Gaslamp Fantasy: The technology level is about that of the Napoleonic Wars, but it exists alongside fantasy elements most prominently, warlocks empowered by kings.
- Going Native: The armies of Lascanne and Denland are fighting through a swamp, and Mallen, the chief scout on the Lascanne side, has spent so long there that his sympathies lie more with the swamp's "indigines" than with either army. He helps his own side in the fight, but always in a way which doesn't conflict with his apparently higher priority of keeping the indigines out of harm's way. It turns out he's from a long line of scholars who have studied the swamp and it's people. Even when the war ends, he stays behind, since he considers the swamp his home anyways.
- The Good King: King Luthrian IV of Lascanne is widely adored by his subjects, and his call to arms against invading republican revolutionaries from Denland is well supported, even as the war drags on. It doesn't hurt that he also has a good amount of Prince Charming about him, being young, handsome, unmarried, and a good dancer as Emily personally discovers. In the end, it turns out that the war which he portrays as a heroic defence was actually the result of his own failed attempt to annex Denland by assassinating its king. He shows no remorse for the countless deaths his scheme caused, even after Denland has won and he's a fugitive. In fact, he has the gall to expect Emily to help raise rebellion in his name instead, she shoots him.
- Impoverished Patrician: The Marshwic family was once fairly wealthy, but a series of misfortunes left it in dire financial straits (and led to the head of the family shooting himself). The family blames much of this on their old rival, Mr. Northway the fact that his fortunes went in the opposite direction (he's now governor of the city) is, to the Marshwics, a great injustice that will surely be corrected as soon as the king learns how wicked Mr Northway is. Mr Northway, while not denying his own corruption, says that Emily's late father was just as bad and that the king cares more for obedience than integrity. He's right.
- I Never Got Any Letters: The Marshwic's are upset about the lack of correspondence from their brother and Mary's husband Tubal, having received only a single brief letter from the former. When Emily ends up at the front and meets Tubal, she learns the reason the army censors letters "to preserve morale", so Tubal knew that any letters he sent would just disappear unless he lied to Mary about what things were like, which he could not bring himself to do.
- In Medias Res: The story starts with Emily seeing one of her comrades/friends killed in battle; it then goes back to Emily's life before being conscripted and gradually works its way up to that point before continuing. (As such, we know that Elise's death is a Foregone Conclusion when Emily first befriends her.)
- Love Triangle: With Emily deciding between Giles Scavian and Mr. Northway. Her preference is for the former, although she never informs the latter of her other suitor until her hand is forced. In the end Emily saves both of them by killing the King, and feels she cannot be with Scavian after killing his king.
- Mad Doctor: The enemy army is under the command of the notorious "Dr. Lam", said to be a physician who rose to power in the chaos of revolution and who now enjoys dissecting captured prisoners. When Emily gets captured, she's taken to see him. It turns out that not only is Dr. Nathanial Lammegeier not a medical doctor (he's an engineer), he's also one of the nicest characters in the book. This isn't the biggest falsehood believed about the Denlanders and their "bloodthirsty revolution", either.
- Military Mage: The only direct magic seen in the series are the King's Warlocks, men who are given the ability to shoot fire after being touched by the King. They're one of Lascanne's primary advantage in the war, as the death of Denland's king has left them without Warlocks of their own.
- Moral Event Horizon: When Emily discussed the potential end of the war with Dr. Lam. Getting either side to accept the rule of the other would be incredibly difficult, and when discussing what might end up happening if Denland wins, he teaches Emily a new work: Genocide. He makes it clear that such a course of action is currently very unpopular in Denland, but not out of the question, especially if the Lascanne people were to resist after losing. When the war does end he reiterates the concern to Emily via a messenger, fearing she may become a figurehead for the resistance, and warns that things like work and even execution camps have been discussed by Denland's parliament. He desperately wants to avoid Denland crossing this line, with his messenger saying "Once we have made ourselves into monsters, we shall never again be men".
- The Quisling: After the war is over, Mr. Northway, formerly Mayor-Governor of Chalcaster for the king of Lascanne, continues in that role despite the change in leadership. His motivations are reasonably good someone has to be in charge, and continuity of government will avert dangerous instability. Of course that's assuming his explanation is true, and not just an admittedly reasonable explanation to excuse his desire to stay in power, but it doesn't do wonders for his public image either way.
- The Remnant: By the end of the book, the army in which Emily is fighting has become this without knowing. Fighting in an inaccessible area with essentially no info about the other front, they don't know that their forces elsewhere have collapsed until the enemy informs them. They don't believe it at first, of course, but are eventually convinced to surrender. They still gain a lot of praise from the citizenry for being the last survivors which becomes important when the fugitive king tries to use Emily, now as much of a war hero as you can get in a defeated country, as the centre of an uprising. The king's own band, however, is not so much a remnant of his old forces as a new gang of bandits he has recruited through bribes and promises.
- Shoot the Mage First: It's noted that being a Military Mage means that the enemy will make killing you their number one priority. By the time Emily gets to the front, of the 19 warlocks that have been sent only 2 remain. Hence those that are left opt to wear normal uniforms rather than their robes, which would only make them stick out from the other troops.
- Simple, yet Awesome: For Denland, inventing the rifle turns out to be this. By milling a spiral groove into the barrels of their muskets and using leather-encased musket balls as ammunition, they create a gun which can shoot at a long-range, is far more accurate than any other firearm of their time, and turns the war with Lascanne into a shooting gallery. At least on the wide open Couchant front, where the sight lines are long enough to actually use them effectively.
- War Hero: Emily, after the events of the war. Rapidly rising in ranks to be one of the highest ranking officers left in the final portion of the army to surrender leaves them widely considered to be one of the greatest heroes of the war by both sides. All this in spite of being on the losing side, and her own protests that others deserve much of the same credit, and that she didn't do anything that couldn't have been done by someone else. It also means both sides consider here to be a likely key figure in any potential rebellions, for better or worse, although she has little interest in it herself, knowing all to well how the war has all but destroyed both countries already, as well as receiving a very explicit warning about what may happen if Denland is forced to continuously fight down rebellions.
- Why Can't I Hate You?: Mr. Northway is (by his own admission) corrupt and self-interested, and his rivalry with the Marshwic family led to its current impoverished status and the suicide of Emily's father. Emily starts out hating him, and makes this clear to him. However, this openness of disregard actually enables them to converse more freely and honestly than if they were pretending to be polite friends, and Emily finds that she's glad to have someone to correspond with who treats her as an equal adversary, doesn't assume he can trick or patronise her, and isn't put off by her barbs and criticisms.